A thin film transistor liquid crystal display (TFT-LCD) is widely applied in a variety of fields of production and life, and it adopts a progressive scanning matrix display arranged by M*N points. When displaying, the TFT-LCD drives various pixels in the display panel to be displayed through a driving circuit. The driving circuit of the TFT-LCD mainly comprises a gate driving circuit and a data driving circuit. Herein, the data driving circuit is used to sequentially latch the input data at regular time according to a clock signal and input the latched data to data lines of a display panel. A gate driving circuit is generally implemented by a shift register unit. The shift register unit converts the clock signal into a turn-on/turn-off voltage which is output to respective gate lines of the display panel respectively. One gate line on the display panel is always oppositely connected to one shift register unit (i.e., one stage of the shift register unit). Progressive scanning of pixels in the display panel is realized by making the respective shift register units sequentially output the turn-on voltage by turns.
On the other hand, as panel display develops, high resolution and narrow frame become the trend of development. In response to this trend, technique of Gate Driver on Array (GOA) emerges. The GOA technique integrates and manufactures the gate driving circuit of the TFT-LCD on an array substrate directly, thereby replacing a driving chip which is bonded with the outside edge of the panel and is made of silicon chip. Since this technique can make the driving circuit on the array substrate directly, there is no need to bond IC and arrange wirings around the panel, which reduces the manufacturing procedure of the panel, decreases the cost of production, and at the same time improves the integration of the TFT-LCD panel, so that the panel realizes narrow frame and high resolution.
Positive drift would occur to threshold voltages of TFT switches in the GOA driving circuit if the TFT switches are driven by high voltages for a long time, which causes reduction of output voltages of the TFT switches, and further causes abnormity of output signals of the GOA driving circuit, thereby affecting stability of the liquid crystal display panel.